Reducing valve

ABSTRACT

A reducing valve having a body, inlet and outlet ports formed therein, a spool slidably inserted in the body, lower and upper covers of the body, a poppet valve formed in the upper cover of the body for adjusting the pressure of a fluid in the outlet port, and an adjusting device for adjusting the position of the spool in the body so as to prevent generation of a surge pressure in the outlet port.

United States Patent Horikiri et al.

[4 1 Nov. 28, 1972 REDUCING VALVE [72] Inventors: Toshihiko Horikiri,Yokohama;

Ryuta Tsuji, Inba, both of Japan [73] Assignee: Kabushikikaisha TokyoKeiki (Tokyo-Keike Co., Ltd.), Tokyo, Japan [22] Filed: Feb. 23, 1971[21] Appl. No.: 117,902

[30] Foreign Application Priority Data [58] Field of Search ..l37/49l,489.3, 492, 492.5,.

2,855,947 10/1958 Lee ..l37/489 X 3,101,738 8/1963 Horlacher 1 37/4891,261,607 4/1918 Peters ..l37/488 X FOREIGN PATENTS OR APPLICATIONS558,611 l/l944 Great Britain ..137/489 Primary Examiner-M. Cary NelsonAssistant Examiner-Robert J. Miller Attorney-Hill, Sherman, Meroni,Gross & Simpson [57] ABSTRACT A reducing valve having a body, inlet andoutlet ports formed therein, a spool slidably inserted in the body,lower and upper covers of the body, a poppet valve formed in the uppercover of the body for adjusting the pressure of a fluid in the outletport, and an adjusting device for adjusting the position of the spool inthe.

137/488, 487, 486, 489 body so as to prevent generation of a surgepressure in the outlet port. References Cited 7 l I 1 7 Claims, 2Drawing Figures UNITED STATES PATENTS 2,853,096 9/1958 Lee ..137/491 92/ l0 7 ll 22 a ti 6' I 1 3 g i Z A B: 5 a! 4 .3, 1 fi REDUCING VALVEBACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to a reducing valve, and more particularly to a reducing valvewhich is provided with a device for preventing surge pressure.

2. Description of the Prior Art A reducing valve is provided in the pipeline system for reducing the pressure of a fluid flowing therethroughdown to a desired value. There are some occasions when an abnormallyhigh pressure (the socalled surge pressure) produced in a hydraulicsystem instantaneously breaks instruments on the side of the load andthis is the source of trouble. Various devices have heretofore beenproposed for preventing the generation of such abnormally high pressure(surge pressure) but most of them are bulky and expensive and henceimpractical. Recently, an accident occurred in which the metal mold ofan injection machine was broken by the surge pressure generated in theoil pressure system during the molding operation thereof. However, nodevices have been proposed for preventing such an accident fromoccurring.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is toprovide a reducing valve having a device with which the throttling orchoking effect of the valve is finely controlled at its starting torender its operation sensitive to thereby reduce the surge pressure.

Another object of this invention is to provide a reducing valve having adevice which permits fine control of the throttling or choking effect ofthe valve at its starting from the outside with accuracy and is simplein construction, effective and highly practical.

Other objects, features and advantages of this invention will becomeapparent from the following description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a cross-sectional view of aconventional reducing valve; and

FIG. 2 is a cross-sectional view, similar to FIG. 1, showing one exampleof reducing valves provided with a surge pressure preventing deviceaccording to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding ofthis invention, a description will be given first of a conventionalreducing valve with reference to FIG. 1. In the Figure referencecharacter B indicates the body of a reducing valve and referencenumerals 1 and 2 inlet (primary) and outlet (secondary) ports for aworking fluid which are formed in the valve body B. Reference numeral 3designates a spool inserted into a bore B formed in the valve body B, 3aan aperture bored in the spool 3, 4 a passage of a small diameter formedin the lower portion and leading to the aperture 3a, and 11a and 11brespectively lower and upper covers of the valve body B. Referencenumeral 5 identifies a spring interposed between the upper cover 11b anda lower stepped portion 3a, of the aperture 30 in the spool 3 and thespring 5 pushes down the spool 3, namely urges it against the lowercover 11a. The upper cover 11b has bored therein an aperture 21, inwhich a seat 22 is fixed, the seat 22 having formed therein an aperture220. A poppet 7 is disposed opposite one open end of the aperture 22a.Reference numeral 10 indicates a spring inserted into the aperture 21for pressing the poppet 7 against the aperture 22a of the seat 22 and 9a handle for adjusting the force of the spring 10 against the poppet 7.Reference numeral 6 designates an oil path formed in the upper cover 11bwhich interconnects the free open end of the aperture 22a of the seat 22and the aperture 3a of the valve body B. Reference numeral 8 identifiesan aperture bored in the upper cover 11b which is a kind of drain portconnecting the poppet side of the aperture 21 with a tank (not shown).At the upper-end portion of the spool 3 there is formed a circularprojection 3b which makes contact with the bore B of the valve body B atthe upper portion of the inlet port 1 to prevent a pressurized fluidflowing into the inlet port 1 from flowing directly into the poppetvalve chamber disposed in the upper cover 11b. This circular projection3b forms a sliding portion of the spool 3 with respect to the valve bodyB. A similar circular projection 3c is formed on the spool 3 at itslower portion. The projection 30 is provided at a place corresponding tothe outlet port 2 in the illustrated condition, so that an orifice A isformed between the circular projection 3c and the upper edge portion ofthe outlet port 2. Further, a similar circular projection 3d is formedon the spool 3 at the lower end portion thereof, namely at a placeopposing the wall of the bore B below the outlet port 2 and theprojection 3d makes sliding contact with the wall of the bore B, belowthe outlet port 2. With suitable selection of the inner diameter of thebore B, or the outer diameter of the spool 3, in the illustratedcondition the fluid flowing into the inlet port 1 is drained out fromthe outlet port 2 through a gap G defined by the spool 3 and the bore Btherebetween and, at the same time, the fluid flows into the aperture22a of the seat 22 through a longitudinal groove G formed in theprojection 3d, a lateral groove G formed in the underside of the spool3, the passage 4, the aperture 3a and the oil path 6, thereby to pressthe poppet 7.

The principles of the operation of such a conventional reducing valve asabove described reside in that when the fluid pressure at the outletport 2 has exceeded a predetermined value thepoppet 7 is opened againstthe force of the spring 10 and then the fluid 'iflowing into the poppet7 is delivered to the tank through the outlet 8 from the gap between thepoppet 7 and the seat 22 irrespective of the pressure variation in theinlet port 1. At this time, the flow of the fluid through the passage 4of the small inner diameter causes a pressure difference between theupper and lower portions of the spool 3 through the passage 4. Namely,the fluid pressure acting on the underside of the spool 3 is greaterthan that acting on its upper portion, so that the spool 3 is moved upagainst the spring 5 to narrow the orifice A defined between thecircular projection 3c of the spool 3 and the upper edge of the outletport 2 of the valve body B and similarly cause a great decrease in thefluid pressure between the inlet and outlet ports 1 and 2. That is, thefluid pressure at the outlet port 2 becomes far lower than that at theinlet port 1. Thus, the fluid pressure at the outlet port 2 is held atthe predetermined value.

In the foregoing, the pressure difference between the upper and lowerportions of the spool 3 for holding the spool 3 at its pressurereduction control position is caused by the flow rate of the fluidflowing through the passage 4 of small aperture. However, while thereducing valve is in its normal operative condition, the poppet 7 isheld in contact with the seat 22, so that no fluid flows through thepassage 4 and the spool 3 is not moved. Therefore, there is nopossibility that the orifice A is completely closed to render thereducing valve inoperative. It is said that the fluid pressuredifference between the inlet and outlet ports is generally required toexceed l0 kg/cm for favorable operation of the reducing valve.

We have carefully examined by an oscillograph the phenomenon that thesurge pressure was produced at the outlet port 2 of the reducing valve.As a result of reaches a predetermined value is short. Accordingly, theresponse of the reducing valve of this invention is very rapid.

In our experiment conducted with a synthetic resin injection moldingmachine employing the reducing valve of this invention in which apressure of 140 kg/cm was reduced down to 50 kg/cm, a surge pressure of120 kg/cm generated on the side of the outlet port 2 in an injectionmolding machine using a conventional reducing valve could be reduced toabout 65 kg/cm and the metal mold was not broken.

In the foregoing the opening of the orifice A is previously made small,but the same results could be obtained even by previous suitableselection of the opening of the orifice A with the use of the screw 14according to the flow rate of the working fluid.

The foregoing example has been described eo employ the piston 12 but itwill be seen that if the screw 14 itself is sealed and its free end isurged against the underside of the spool 3, the piston 12 and the O-ring13 canbe omitted.

this, it has been clarified that the surge pressure is caused by animproper opening of the orifice A and a time lag due to dull operationof the spool 3.

Accordingly, the present invention resides in a reducing valve providedwith a device by which the operating distance of the spool 3 ispreviously shortened according to the flow rate of the working fluid andthe opening of the orifice A is accurately adjusted at the starting ofthe valve taking note of suitable adjustment of the opening of theorifice A.

With reference to FIG. 2 one example of this inven- I tion willhereinbelow be described in detail. In the figure reference numerals andcharacters corresponding to those in FIG. 1 designate similar elements.Their constructions and operations are substantially the same as thosedescribed with FIG. 1, and hence no detailed description will berepeated.

Reference numeral 12 designates a piston which is inserted in the lowercover llaof the reducing valve and contacted with the lower end surfaceof the spool 3 for adjusting the opening of the orifice A. Referencenumeral 13 indicates a packing such as O-shaped ring provided at theintermediate portion of the piston 12, 14 an adjustment screw for thepiston 12 the upper end of which adjustment screw 14 engages with thelower end of the piston 12 and the lower end portion of which adjustmentscrew 14 projects out from the lower cover 1 la and 15a lock nut of theadjustment screw 14.

A description will be given of the operation of this invention depictedin FIG. 2.

The piston 12 is moved up a suitable distance by turning the adjustmentscrew 14 from the outside of the reducing valve so that the opening ofthe orifice A may be of a suitable value at the starting of theoperation of the reducing valve in accordance with the flow rate of theworking fluid as previously described, and then the adjustment screw 14and consequently the piston 12 is fixed by clamping the lock nut 15.

Since the distance. of movement of the spool 3 is previously. shortened,the opening of the orifice A is previously made'small in advance.Therefore, the time for the movement of the spool 3, namely for changingthe orifice until the pressure of the reducing valve With an attachmentof a simple'additional device and its adjustment from the outside of thereducing valve, the present invention readily prevents generation of thesurge pressure without fail, and hence is highly practical and can bewidely used for various purposes.

It will be apparent that many modifications and variations may beeffected without departing from the scope of the novel concepts of thisinvention.

We claim as our invention l. A reducing valve comprising a body havingan inlet port and an outlet port formed therein, a spool slidablyreceived in the body and movable from a first position providing a flowpassage interconnecting said ports to a second position blocking flowbetween said ports, means biasing the spool to the first position, meansfor applying the fluid pressure at the outlet port against opposite endsof the spool, valve means for releasing the fluid pressure appliedagainst one end of the spool to cause the spool to move toward saidsecond position to restrict flow between said ports, and adjustablemeans for varying the position of the spool in said first position tovary the size of the flow passage and to prevent generation of a surgepressure of the fluid in the outlet port.

2. A reducing valve according to claim 1, wherein said adjustable meansis a screw threaded into said body having one end making contact withthe other end the screw has a lock nut for locking the screw in apredetermined position in said body.

6. A reducing valve comprising a body, inlet and out- 1 let ports formedtherein,-'a spool slidably inserted in the body, a lower cover of thebody, an upper cover of the body, a valve provided in the upper coverfor adjusting the pressure of a fluid at the outlet port, and means foradjusting the position of the spool so as to prevent generation of asurge pressure of the' fluid in the outlet port, said means foradjusting the position of the spool consisting of a screw screwed intothe lower cover and a piston having provided thereon an O-ring andinserted into the lower cover, the upper end of the piston makingcontact with the underside of the spool and one

1. A reducing valve comprising a body having an inlet port and an outletport formed therein, a spool slidably received in the body and movablefrom a first position providing a flow passage interconnecting saidports to a second position blocking flow between said ports, meansbiasing the spool to the first position, means for applying the fluidpressure at the outlet port against opposite ends of the spool, valvemeans for releasing the fluid pressure applied against one end of thespool to cause the spool to move toward said second position to restrictflow between said ports, and adjustable means for varying the positionof the spool in said first position to vary the size of the flow passageand to prevent generation of a surge pressure of the fluid in the outletport.
 2. A reducing valve according to claim 1, wherein said adjustablemeans is a screw threaded into said body having one end making contactwith the other end of the spool as the spool assumes the first position.3. A reducing valve according to claim 1, wherein said adjustable meansis a screw threaded into said body engaging a piston disposed in thebody for adjusting the axial position of the piston in said body, saidpiston engaging said spool to determine the axial position of the spoolin the body as it assumes the first position.
 4. A reducing valveaccording to claim 3, wherein the piston has provided thereon an O-ring.5. A reducing valve according to claim 3, wherein the screw has a locknut for locking the screw in a predetermined position in said body.
 6. Areducing valve comprising a body, inlet and outlet ports formed therein,a spool slidably inserted in the body, a lower cover of the body, anupper cover of the body, a valve provided in the upper cover foradjusting the pressure of a fluid at the outlet port, and means foradjusting the position of the spool so as to prevent generation of asurge pressure of the fluid in the outlet port, said means for adjustingthe position of the spool consisting of a screw screwed into the lowercover and a piston having provided thereon an O-ring and inserted intothe lower cover, the upper end of the piston making contact with theunderside of the spool and one end of the screw making contact with thelower end of the piston, the position of the spool being adjustedthrough the piston by adjusting the screw.
 7. A reducing valve asclaimed in claim 6 wherein the screw has a lock nut for locking thescrew at a predetermined position.